Roofing element and method of making the same



1,625,888 Ap 26 1927' J. H. GlLLlS ROOFING ELEMENT AND METHOD OF MAKINGTHE SAME Filed Aug. 15 1923 NVENTOR J M8 ATTORNEYS I such Patented Apr.26, 1927.

UNITED. STATES PATENT OFFICE.

JULIUS H. GILLIS, OF ELIZABETH, NEW JERSEY, ASSIGNOR, BY MESNEASSIGNMENTS, T0 ANACONDA SALES COMPANY, A CORPORATION OF DELAWARE.

ROOFING ELEMENT AND METHOD OF MAKING THE SAME.

Application filed August 15, 1928. Serial No. 857,488.

This invention relates to roofing elements and processes for making. thesame, and has to do primarily with roofing elements in the form ofboards, strips, tiles, single or multiple shingles, and the like. Theseelements are of the composite type and consist of a base formed ofvarious materials wellknown in the art under the general name of roofingcompositions, and a protective metallic layer or coating applied to thebase to form a weather surface therefor.

Composition roofings are in wide use at the present time, and serve toreplace roofing materials hitherto used, such, for instance. as woodenshingles, slate, etc. These composition roofings are formed of paper,felt, burlap, or similar materials, impregnated with water-proofingmaterials as bituminous substances, magnesite compositions, and variousother non-hygroscop c, heat insulating materials held together with asuitable binder. Such composition roofing material is used in a varietyof forms, as, for instance, strips,

- s ngle or multiple shingles, tiles, etc. The

multiple shingles consist of a strip of roofing of appropriatedimensions having an indented edge so formed that when these elementsare laid in courses in the usual manner the indented edge is exposed soas to give the usual appearance of a shingle roof.

Composition roofings of the type above generally referred to havenumerous advantages, due to their comparatively low cost,

' easy method of application,and heat insulating quantities. However,when such elements are laid in place on the roof in overlapping coursesthe exposed portion is likely to warp or curl, and after periods of usethe composition deteriorates due to the volatilization of the oils usedin their manufacture.

' Also such composition materials are not al of metal has also been incommon use combine the advantages of the two types previously referredto, is shown and described in the Patent No. 1,449,058, granted March20, 1923, to Thomas. Robinson. This element consists of a compositionbase of various forms, prepared by methods which are well known. On thatsurface of the element which is to be exposed to the weather, there isapplied athin coating of a non-corrodible metal, such, for instance, ascop er or zinc. This metallic coating is limitec to the Weather surfaceof the element and it serves to stiffen the base to prevent warping andcurling, to protect the relatively soft base materials, and to preventdeterioration caused by volatilization of the base oils. By using a thinlayer of metal and by limiting this layer tothe Weather surface of theelement, the cost of the new type of roofing is but little greater thanthat of the unprotected base and such elements may be laid as easily asordinary composition roofings and without that degree of care which isnecessary in the case of metallic roofings to revent leaks. In thepatent above referrec to the metal coatmg is applied directly to thesurface of the base in various ways, as for instance, byelectrodeposition. In the co-pending application of Thomas Robinson,Ser. No. 618,246, filed February 10, 1923, there is shown and describeda somewhat similar element which is given an attractive appearance bythe application of a layer of grandular material such as crushed slateor crushed petroleum coke pressed into the surface of the base beforethe metallic layer is applied. Also in the co-pending application ofThomas Robinson, Ser. No. 652.563,

filed July 19, 1923, there is shown and described a process for makingelements which consist of a base and a preformed metallic layer which isapplied thereto by pressure. In this particular process the base is ofordinary composition and may have either a lain or granular surface towhich a pre ormed metallic layer or coating, cut to the approprate sizeand shape, is applied by the application of pressure sufiicient to causethe metal to conform to the irregularities of the base and adherethereto.

The present invention is intended to improve the quality of the roofingelements made by either the electrolytic or pressure processes, abovereferred to, and is intended further to provide a process by which thereis secured a stronger adherence between the metallic coating and thebase. It is adapted especially for use with electrolytic processes forapplying the coating for in such processes it will be clear that it isnecessary to give the base a coating of electrical conducting materialbefore the metal is applied thereto. The conducting material which isordinarily used for this process is powdered graphite, which is held inplace by the use of a suitable adhesion. In preparing the elements forthe deposition of the metal their weather surfaces are sprayed orotherwise treated with an adhesive which may take the form of asaturated solution of asphalt in carbon tetrachloride. A layer ofpowdered graphite is then dusted or brushed thereover and when theadhesive dries the raphite is firmly held in place. This conductingcoating is necessary for the electrolytic rocesses in which the metal isdeposite over the coating in such a wa as to conform to theirregularities of the use so that a good binding effect is produced.However, it sometimes happens, due to carelessness on the part of theworkman, that the conducting material is applied unevenly or in a muchthicker layer than is necessary for carrying on the deposition, and iftoo thick a layer of graphite, which has lubricating qualities, isapplied to the base lying between it and the metallic layer extremechanges in temperature causing expansion and contraction of the metal,may result in loosening this layer from the base.

The object of the present invention may be restated then, as theprovision of a process by means of which the metallic layer is boundfirmly directly to the base even though there is an intervening coatingof conducting material and this process improves the quality of theroofing even in those cases where the layer is applied by pressure andno conducting material intervenes between the metal and the base. Incarrying out the process, I take advantage of the fact that the basecontains a plastic substance which softens and expands upon heating andI heat the metallic coating after the latter has been a lied to the baseeither by pressure or depositlon, confining this heat to the metal insuch a way that only a thin stratum of the base immediately underlyingthe coating is heated by conduction. This application of heat causes theplastic material on and in the base to soften and swell and during thisheating I apply pressure to the metallic layer so as to cause thesoftened plastic material to wet the layer over all its surface incontact with the base. The heat is applied and regulated in such a waythat the base itself is not heated throughout its thickness and I preferto apply the.

as to give the desired effect without soltening the base so that theelement cannot be readily handled.

In order to secure a good bond between the base and the layer I preferto use a base which contains asphalt as an ingredient although othersimilar materials used for binders in the past are also satisfactory.The new process, however, is applicable in connection with any ty e ofbase, whether or not it is impregnatecFwith asphaltic material, althoughin'the latter case it is preferable to use an adhesive containingasphalt for binding the conducting coating to the base. If no conductingcoating 15 to be used, as in the case of preformed metallic layersapplied by pressure, then it is preferable to apply a thin film of ashalt or similar material to the base before t a metal is pressed inplace thereon.

In taking advantage of the plastic material on and in the base forcausing the layer to adhere thereto, there are several essentials whichmust be borne in mind in connection with the heating step. I have foundthat the bond is the stronger, the hotter the layer is made, but inapplyin this heat it should be limited to the layer because if the heatenters the base to any reat extent, it is likely to cause volatilizationof the oils and to soften the base and render it flexible so that theelements after the heating cannot be readily handled but must be storedand allowed to cool in such a way that they will not warp. Again it isnecezsary that the heat should beuniform throughout the metallic layer,otherwise bulging of the la er is likely to occur with the result that wen the source of heat is removed the layer will not conform properly tothe surface'of the element. It is also necessary that the heating shouldbe carried on rapidly and that the layer should be raised to atemperature sufficient to soften the plastic material in the base onlyto a very slight depth. The longer the heat is a plied, the greater willbe the layer of the ase which is softened, and while it is onlynecessary to heat the plastic material in a thin stratum of the base inorder to secure a firm bond, slow-heating does not improve the qualityof the bond but on the other hand causes the heat to be conducted intothe base so that it is sof' tened. The application of pressure duringthe heating improves the quality of the bond but such heat and pressurecannot be carried on by any of the ordinary methods such as by passingthe elements through steam or gas heated rolls because the heating soproduced is too slow. Also it is not possible to carry on the heating bythe application of flames directly on the metal, masmuch as suchtreatment results in the deposition of combustion products on the metalinjuring its appearance and in some cases causing a. slight corrosion.Heating by flame also has the disadvantage that it is almost impossibleto secure an even and uniform application of heat, and, as haspreviously' been explained, this results in bulging of the layer.

I have found, however, that application of heat with the desiredrapidity under the proper regulation and without .theseveral otherdisadvantages of hot roll or flame heating, may be carried on by makinguse of the heating effect of the electric current. For this purpose Iuse presses or rolls provided with suitable contacts which cause acurrent of the desired intensity to flow through the metallic layer.This rapidly generates heat which is localized and confined in the layerand which does not spread to any appreciable extent into the base. Byproperly regulating the current the heating operation may be carried oneconomically and with great ra idity, and the elements which have beensu jected to the application of heat and pressure may be easilysupported in a way which prevents warping or curling of the base orbulging of the layer. Also by generating heat in the layer itself thereis no possibility of the layer bulging or expanding away from the base.

Various mechanical devices may be used for carrying on the presentprocess, but in the accompanying drawings I have illustrated variousforms of mechanism which are satisfactory for such purposes. In thesedrawings,

Fig. 1 is a cross-sectional view of a smooth surface element showing themetallic layer applied thereto,

Fig. 2 is a View similar to Fig. 1, but showing the metal applied overthe granular surface,

Fig. 3 is a plan view of a multiple shingle element showing the outlineof the coating and location of the contacts,

Fig. 4 is a view similar to Fig. 3, showing the modifications necessaryin connection with a single shingle element,

Fig. 5 is a view similar to Fig. 3 but showing the contacts in modifiedform,

Fig. 6 is a diagrammatic view in side elevation of a pressure deviceprovided with contacts,

Fig. 7 is a plan view of a flashing strip having a metallic coating,

Fig. 8 is a view in side elevation of a modified form of device fortreating such strips,

Fig. 9 is a cross-sectional view of a detail of the pressure rolls used,

Fig. 10 is a phantom view of one of the rolls showing the current paths.

Referring now to the drawings, the roofing element is seen to consist ofa base 11, provided with a metallic coating 12, extending over theweather surface of the base and applied in such a way as to conform tothe rregularities thereof. In the element shown in Fig. 1. the base isillustrated as having irregularities which are shown somewhatenlargedfor purposes of illustration. It

will be understood that the presence of these to be applied. In Fig. 2the base is shown to be provided with a granular layer 13, disposed overthe surface thereof. This granular layer, as has previously beenexplained, may consist of crushed slate or crushed coke which has beenpressed into the surface of the base while the latter is still soft. Theelement illustrated in Fig. 2- has a metallic layer 12, applied overthese granules in such a way as to enter the interstices between'thegranules and so conform to the irregular surface. In Fig. 3 the element14 is of the multiple type a d one edge is provided with cut-outs llwhich serve to define three separate shingles 16 These cut-outs areformed so that when the multiple element is laid in place only theprojecting portions defined by the cut-outs are exposed, and a roofformed of multiple elementshas the usual appearance of an ordinaryshingle roof. In this form of element each of the shingles definedthereon is provided with a metallic layer 16, terminating at the rearend in a neck 17 which is extended so as to underlie thev cut-out of theshingle of the overlying course. With this arrangement it will be seenthat all the exposed portions of the. shingle are covered with metal sothat to all intents and purposes the roofing may be considered to be acontinuous metallic roofing. The ele ment illustrated in Fig. 4 is asingle shingle of the usual outline having a coating 18 which terminatesin a. triangular portion 19 which serves to underlie the space be tweenadjacent elements of the overlying course. As these shingle elements areusually laid by hand the portion which underlies the space between theelements of the next course above is made somewhat greater than the neck17 so as to allow for carelessness of the workmen in applying theshingles.

The new process may be practiced with out regard to the particular shapeand size Ill) of the roofingelements to be treated, but slightmodifications are necessar in the construction of the resses'or rol s asthe case may be, and a so in the location of the contact members,according to the outline of the elements and the sha e and size of themetallic layer thereon. or convenience the elements have been shown in aform which is widely used at present, and the necessary contacts andelectricalconnectlons are designed for use with such elements,

but it will be understood that the general:

principles here set forth are applicable regardless of the particularoutline which the elements have.

Referring now to Fig. 6, the ress which I make use of has a bed 20, t eworking face of which is preferably provided with a layer 21 of yieldingmaterial, such as rubber. Mounted above the bed is a movable plunger 22,which may be mounted to 'move in a standard in accordancewith the usualpress construction. The face of this plunger is provided with a yieldingcushion surface 23 which ma be made of rubber suitably treated towithstand the temperatures which are to be em loyed. This rubber cushionwill be preferably secured 'in place in the plunger in any convenientway, so that it may be readily removed and replaced when occasiondemands. Secured in the face of the plunger and insulated from the bodythereof, are spaced contacts, these contacts lying flush with thesurface of the cushion so that when the plunger is depressed against anelement laid on the bed the contacts will strike the face of the elementwhile ressure is exerted through the cushion to iold the metallic layerof the element firmly against its base. It will be understood that theshape and size of the plunger will depend upon the shape and sizeof theelement which is to be treated, and the spacing of the contacts in theface of the plunger will also depend on the form of the metallic layerwhich has been applied to the element base. In Fig. 3 there are showncontacts suitable for a multiple element which consists of threeshingles united along their rear edges. Located in the face of theplunger are spaced contact-s 25 which will engage the metallic layer ofthe element along its rear edge where the neck portion joins the body ofthe layer.

H Contacts 26 serve to engage the front edge of each layer and thecurved contacts 27 are spaced so that when the plunger is depressedthese contacts will engage the end of the neck portions. The contact 25,as is illustrated in the right of Fig. 3, is connected to one terminalof a source of power and the current accordingly enters the contact 25and spreads in both directions through the metallic coating bein takenoff through contacts 26 and 27. hese contacts are then joined by aconductor 28 which lies within the face of the plunger and the conductor28 is in turn connected to the contact 25 for the next metallic layer.The current spreads through this layer as before, passes out throughcontacts 26 and 27, and enters the central contact 25, being finalltaken off by means of a conductor 29 which connects the contacts 26 and27 for'the layer at the left in Fig. 3. This conductor is then connectedto the other side of the line. "It will be clear that when the contactsare out of engagement with the layers of the element no current willflow but immediately upon depression of the plunger into contact withthe element current will flow through the metallic layers, as has beenexplained.

The contacts illustrated in Fig. 4 have been designed to take care ofthe'particular form of metallic layer used in a single shingle. Thereis'a central contact bar 30 across the layer at the base of thetriangular portion, an annular contact 31 which engages the layer at theapex and another contact 32 which engages the front edge of the layer.The current aths are similar to those previously described, the currententering through the central contact and spreading through the layer, tobe taken off through the contacts 31 and 32. In Fig. 5 there is shown asomewhat modified layout for the contacts which shows the use ofconductors within the face of the plun er. In this arrangement there isprovide a contact 33 which engages'one metallic layer along the top ed eand along the side of the mp1; portion. nother contact 34 extends alongthe front edge of one la er, then rearwar 1y to overlie the edges 0adjacent layers, then along the edge of the second layer, and up andaround the neck portion, as before. Contacts similar to 34: are used inany number desired, depending on the number of shingles in the element,and the current is then removed through a contact 35 which extends alonthe front edge of one layer and rearwar 1y along its side. In thisarrangementcurrent will enter contact 33 and travel through the metalliclayer to the contact 34, passing through the contact to the next layer,thence through the layer to the next contact 34, and thence out throughcontact 35. The contacts are so designed that current will flow throughall portions of the metal layer, heating it evenly and uniformly.

In Fig. 7 there is illustrated a form of roofing material useful forflashing stri s. This consists of a long strip of base material having afacing of metal and for ap lying heat and pressure to such a stri 1 havefound it convenient to make use 0 pressure rolls provided withelectrodes on the surface thereof. Such an arrangement is illustratedIII pair of rolls 36 and 37.

face of the roll. These electrodes may be connected to a suitable sourceof power by means of brushes or other contact arrangements and aredesigned so that the current enters one contact 39 of Fig. 10, andpasses out the other 40. The current passing be\ tween the electrodeswill accordingly travel through the metallic layer on the strip and inits passage will spread, through paths as illustrated at 41 in Fig. 10.The strip 42 is shown to enter the pressure rolls from the left in Fig.8, passing through contact rolls 36, 37 and then passing through aseries of rubber pressure rolls 43, which exert regulated pressure onthe strip. The current may be so selected that the heating will becarried on rapidly and the strip is moved with a steady uniform movementthrough the rolls. If it is desired to increase the rate of heating itispossible to make use of a series of contact rolls 36, 37, as shown atthe, right in Fig. 8, the strip moving from these rolls being latersubjected to pressure between rollers similar to those illustrated at43. In its passage through the rolls the metallic layer is heated by thecurrent travelling between the electrodes and pressure is applied notonly by the electrode rolls but also by the succeeding rubber pressurerolls, so that when the strip emerges from the apparatus the binding ofthe metal to the base is complete. It is necessary that the pressurerollers 43 should be spaced and aligned in such a way as to maintain thestrip in its straight condition withoutsagging or bending untiltheflp'lastic material which has been caused to-wet the metal during theheating has set, as ot erwise the metal might pull away from the b soand the desired adherence be lost.

I have found that a satisfactory bond is secured by heating the copperto approximately 350 F., although the degree of heat will naturally deend on the character, of the plastic material which serves to producethe bond. Theparticular degree of heat above referred to has been foundsatisfactory in the case of an element to which the metallic layer hasbeen applied by electro-deposition' over a thin film of graphite held inplace by an adhesive containing asphalt. The pressure required in theabove example is ap-- proximately 25 pounds per square inch and I havealso found that a current of approximately 150 amperes per inch of widthof the coating is about the mostsatisfactory intensity. The voltagerequired to produce such a current in this particular type of element isapproximately one half 9. volt for contacts whlch are five inches :1)art, and the applicat1on of such a current for a period oftwentyseconds produces the desired heating elfect.

ril have found that-the application of heat as above described causesthe plastic material of the base to expand and swell with a slightbubbling effect which causes this soft-' ing layer with the result thatthis layer is absorbed' in the base and accordingly does not intervenebetween the surfaceof the base and the metal. This is particularly truewhere the conducting layer is graphite which has been caused to adhereto the base by means of an adhesive containingasphalt.

The process above described results in a thorough binding of the metalto the base throughout the surface of the metal and is a plicablewhether the metal has been appiied by electro-deposition or by pressure.In the first case, however, it has the advantage of causingtheconducting material to be absorbed into the base and this is ofpeculiar advantage where graphite is used owing to the lubricatingqualities of the graphite. The process, however, is of equal ap licationwhere the performed layer is applied by pressure and is also capable ofap lication to roofing elements made in accorc ance with the processdisclosed in the co-pending application of Thomas Robinson, Ser. No.606,339, filed Dec. 11, 1922, wherein the metal is applied in the formof a fine powder bound to the base by a suitable adhesive.

The generation of the heat in the metallic layer not only serves toconfine and localize the heating effect so that the base is not.

rendered flexible, but the element may be readily handled at thecompletion of the process, since the heat does not extend into the baseto any appreciable extent. I have also found that this a plication oflocalized heat has another incidental advantage inasmuch as the heatingis carried on under those conditions which are best for annealing themetal layer. This results in improving the quality of the metal, as wellas producing a more perfect bond.

The contacts which are used for causing the current to flow through themetal may be of copper, iron, or nichrome, and will last indefinitely.Also the cushion which is applied to the face of the plunger and to therollers may be made of rubber of such characteristics that it willreadily withstand the degree of heat required and since this heat is ofcomparatively low temperature and is applied for a comparatively shortlength of time, the cushions will last for an indefinite period. It willaccordingly be seen that the process is relatively inexpenoperation.

sive to carry on and the bond between the metal and the base is notproduced by added materials but by materials which are present in thebase or necessarily applied thereto in connection with the applicationof the conducting material.

It will be understood that the moving plunger in the press is preferablypowerdriven, and is arranged so that the pressure to be exerted by itmay be regulated. The simplest form of press will be provided with asingle lunger of such size as to act on a single. e ement at a time.Ordinarily a plunger arranged to act on a four-shingled unit will be themaximum size used, although multiple shingle units may be treated in asingle unit press, pressure being exerted successively on each of theshingle coatings. Ordinarily it is most convenient to arrange thepresses in airs so that one workman can feed roofing e ements to them inalternation, and the time required for the application of heat is justabout suflicient for placing anew element in the press and starting theheating From the presses the elements are conveyed to storage-warehousesor shipping platforms and since the metal layer is comparatively thin itwill radiate heat with such rapidity that the elements may be handled bythe workman as soon as they are removed from the press. Also theelements are not appreciably softened during the the heating operation,and it is not necessary to permit them to cool off before they arehandled.

I claim:

1. A method of making roofing elements, which comprises preparing a basecontainin a plastic substance, allowing the plastic su stance to assumea non-adhesive condition, applying a metallic layer to the surface ofthe base, and simultaneously heating the metal and pressing it againstthe base, the heating of the metal being carried on to an extentsufiicient to soften the plastic substance and render it adhesive.

2. A method of manufacturing roofing elements, which comprises preparinga base containing a plastic substance and having an irregular surface,allowing the plastic substance to assume a non-adhesive condition,applying a metallic layer over the irregular surface of the base in suchmanner as to conform to the irregularities thereof, and simultaneouslyheating the metal and pressing it against the base, the heating of themetal being carried on to an extent suf-' ficient to soften the plasticsubstance so that it wets and adheres to the metal.

3. The method of manufacturing roofing elements, which comprisespreparing a base containing a plastic substance, allowing the plasticsubstance to assume a nonadhesive condition, applying a metallic layerto the surface of the base, pressing the neaaaea layer of metal againstthe base, and, while the metal and base are so held, generating heat inthe layer sufiicient to cause the lastic substance in the base to softenan adhere to the under surface of the metal.

4. The method of manufacturing roofing elements, which comprisespreparing a base containin a plastic substance, allowing the plastic sustance to assume a non-adhesive condition, appl ing a metallic layer tothe surface of the base, and passing an electric current through thelayer to heat the latter to an extent sufiicient to soften the plasticsubstance to cause it to wet the layer and adhere to it.

5. The method of manufacturing roofing elements, which comprisespreparing a base containing a plastic substance, allowing the plasticsubstance to assume a non-adhesive condition, applying a metallic layerto the surface of the base, pressing the base and layer into intimatecontact, and, while the base and layer are so held, causing an electriccurrent to flow throu h the layer to raise the temperature of the latterto an extent suflicient to soften the plastic substance and render itadhesive.

6. The method of manufacturing roofing elements, which comprisespreparing a base containin a plastic substance, allowing the plastic sustance to assume a non-adhesive (ondition, applying a conductivematerial to the surface of the base, electrodepositing a metallic layerover the conducting coating, holding the layer and base in intimatecontact, and heating the layer to an extent sufficient to soften theplastic substance and render it adhesive.

7. The method of manufacturing roofing elements, which comprisespreparing a base containing a plastic substance, electrodepositing ametallic layer on the surface of the base, pressing the base and layerinto intimate contact, and, during the pressing operation, generatingheat in the metallic layer to raise its tem rature sufficiently tosoften the wet and ad ere to the metal.

8. The method of manufacturing roofing elements, which comprises coatinga base with a film of asphalt, allowing the asphalt to cool and harden,applying a metallic layer over the asphalt coating, pressing the baseand layer into intimate contact, and, during this 0 eration, generatingheat in the layer su cient to soften the as halt coating to cause thelatter to wet and a here to the under surface of the metal.

9. The method of manufacturing roofing elements, which comprises coatinga base with an asphaltic film, allowing the film to cool and harden,applying a conducting coating over the film, electrodepositing a metallayer over the conducting coating. and generating heat in the layer toraise Ill) lastic su stance to cause it to its temperature sufficientlyto cause it to soften the asphaltic film so that the latter adheres tothe metal.

10. The method of manufacturing roofing 7 elements, whichcomprisespreparing a base containing a plastic substance, allowing theplastic substance to assume a non-adhesive condition, applying aconducting coating to the base, electrodepositing a metallic layer overthe coating, and heating the layer to cause it to soften the plasticmaterial to an extent sufficient to cause the layer to absorb theconducting coating and wet and adhere to the layer.

11. The method of manufacturing roofing elements, which comprisespreparing a base containin a plastic substance, allowing the plastic sustance to assume a non-adhesive condition, applying a metallic layer tothe surface of the base, and progressivel uniting the base and layer bygenerating eat in the layer while it is in position on the base, theheating being carried on to an extent sufficient to soften the plasticsubstance and render it adhesive.

12. The method of manufacturing roofing elements, which comprisespreparing a base containing a plastic substance, allowing the plasticsubstance to assume a non-adhesive condition, applying a metallic layerto the surface of the base, and uniting the base and layer byprogressively ressing the base and layer into contact and simultaneouslygenerating heat in the metal to an extent sufficient to soften theplastic substance and render it adhesive.

13. The method of manufacturing roofing elements, which comprisespreparing a base containing a plastic substance, allowing the plasticsubstance to assume a non-adhesive condition, applying a metallic layerto the surface of the base, and uniting the base and layer byprogressively pressing the layer into contact with the base and causingan electric current to flow through the layer along a path movingthroughout the length of the layer, the current raising the temperatureof the metal to an extent sufiicient to cause it to soften the plasticmaterial and render it adhesive.

14. The method of manufacturing roofing elements, which comprisespreparing a base containing a plastic substance, allowing the plasticsubstance to assume a non-adhesive condition, applying a metallic layerto the base, and passing the base and layer through pressure rolls andcausing an electric current to flow through the layer along the line atwhich the maximum pressure is exerted, the current raising thetemperature of the metal to an extent suflicient to soften the plasticmaterial and render it adhesive.

15. A roofing element which comprises a base coated with a plasticsubstance, a conducting coating over the plastic coating, and anelectrodeposited metallic la er over the conducting coating and bounbase in part by the plastic substance which adheres to the under surfaceof the metal.

16. A roofing element which comprises a base coated with an asphalticcompound, a coating of graphite on the surface of the base, and anelectrodeposited metallic layer to the over the graphite, the metalliclayer in part adhering to the graphite and in part being held to thebase by means of the asphaltic compound which contacts with the undersurface of the metal and adheres thereto.-

In testimony whereof I aflix my si ature.

JULIUS H. GI LIS.

